SUMMARY' Autism Spectrum Disorders (ASD) currently afflict 1-2% of all children in the United States and negatively impact social, behavioral, and cognitive development. Children with ASD often display a variety of immune related abnormalities and postmortem human ASD brain samples show alterations in microglia morphology and density, suggesting a disruption in the critical link between the developing immune system and fetal brain. Microglia are the resident immune cells in the brain and may mediate many of the impacts of inflammation on the developing fetal brain. It is currently unknown how either genetic or environmental ASD risk factors alter microglial regulation and if microglial alterations are in response to ASD pathology, directly contribute to it, or both. This proposal will directly examine epigenomic regulation of microglia during normal development and compare how four unique ASD risk mouse models disrupt microglia function by examining epigenomic control of microglial gene expression (Aim1), microglial cell surface receptor expression (Aim2) and the functional implications of altered gene expression, methylation, and cell surface receptor expression (Aim2). Our main hypothesis is that both environmental and genetic ASD risk factors will alter microglial gene expression, DNA methylation, cell surface receptor expression and function through a set of commonly misregulated pathways and gene targets. We will utilize state-of-the-art whole genome bisulfite sequencing, RNA sequencing and unbiased proteomics to fully profile microglia from each ASD risk model (two different gestational immune activation environmental models (polyI:C and maternal allergic asthma) and two genetic models (Chd8+/del5 and Fmr1 KO mice). Using a novel systems biology approach we will combine the collected multi-omics datasets into weighted gene network models to identify key pathways disrupted by both genetic and environmental risk factors for ASD. Identified targets will be further examined for therapeutic potential by directly testing their impact on microglial function including assays for cytokine release and phagocytosis. To conduct the proposed research aims I have assembled a mentoring team with expertise in all aspects of the proposed work. My mentor, Dr. LaSalle, is an expert in DNA methylation analysis and neurodevelopmental disorders. Dr. Paul Ashwood is an expert in immunology in ASD and Dr. Hormozdiari is an expert in weighted gene co-expression network development. Dr. Phinney and the Proteomics Core at UC Davis will assist with cell surface receptor analysis. I will receive additional guidance in microglial biology from our collaborator Dr. Jin and CHD8 biology from Dr. Nord. Together my mentoring team will guide me through the research component and my own career development. As part of my integrated training plan I will gain critical skills in scientific communication, grant writing, responsible conduct of research and lab management. I will also complete additional didactic training in neuro-immunology and microglial biology. Together this comprehensive training plan will provide me with the additional expertise necessary to transition to my long-term goal of becoming an independent investigator. Overall, outcomes from this work will expand our understanding of microglial epigenomic regulation in ASD and identify key, novel therapeutic targets for further development in my own independent research program.